It is well-known that the atomic nuclei of certain materials possess magnetic moments which arise out of their inherent angular momentum or spin properties. These special properties of certain materials form the principle upon which the nuclear gyro operates.
In U.S. Pat. No. 3,778,770, assigned to the same assignee as the present invention, there is disclosed an optically pumped nuclear magnetic resonance gyroscope device in the preferred embodiment of which two different isotopes of mercury are utilized in the cells of two interconnected spin generators. As taught therein, each spin generator comprises a mercury absorption cell containing .sup.199 Hg and .sup.201 Hg, which is subjected to a DC magnetic field H.sub.0 and to an AC magnetic field, H.sub.1 perpendicular to field H.sub.0. The magnetic fields H.sub.0 of the two cells are described as being equal and antiparallel to one another. The mercury absorption cells are optically pumped by a circularly polarized beam of light to increase the magnitude of the net magnetic moment and means are provided to derive a readout signal representative of angular rotation about a given axis by comparing the phase outputs of the two spin generators.